The present invention relates to a motion picture camera. More particularly this invention concerns a method of and an arrangement for controlling the diaphragm of such a camera during fade in and fade out.
A motion-picture camera is known having an automatic diaphragm control that is controlled by a light sensor provided in back of the diaphragm. The diaphragm itself is adjusted by a step motor that is driven by an oscillator, the oscillator frequency being increased to stop down the diaphragm and vice versa.
It is frequently desirable to fade in and fade out with a motion picture camera so as to avoid abrupt changes between different scenes. For fade in the diaphragm aperture must be regularly increased from a relatively small to a relatively large size. For fade out or dissolve the diaphragm aperture must be regularly stopped down. It is essential in such an operation that the film not be overexposed at maximum aperture at the end of a fade in or underexposed with the lens fully stopped down at the end of a fade-out sequence.